Memory is one type of integrated circuitry, and is used in computer systems for storing data. Integrated memory is usually fabricated in one or more arrays of individual memory cells. The memory cells may be volatile, semi-volatile, or nonvolatile. Nonvolatile memory cells can store data for extended periods of time, and in some instances can store data in the absence of power. Volatile memory dissipates and is therefore refreshed/rewritten to maintain data storage.
The memory cells are configured to retain or store information in at least two different selectable states. In a binary system, the states are considered as either a “0” or a “1”. In other systems, at least some individual memory cells may be configured to store more than two selectable states of information.
Dynamic random access memory (DRAM) is one type of memory, and is utilized in numerous electronic systems. A DRAM cell may comprise a transistor in combination with a charge storage device (for instance, a capacitor). DRAM has an advantage of having rapid read/write; but has disadvantages of being highly volatile (often requiring refresh of several hundreds of times per second) and of being erased in the event of power loss.
It is desired to develop improved memory devices.